Quartersawn vs flatsawn movement

There is no single answer, and that is the finding

Ask how much less quartersawn moves and you will be told "about half" by nearly every source that answers at all. Change the species in the tool above and watch that claim fall apart. Greenheart gains 8%. Black walnut gains 30%. Eastern white pine gains 66%. The spread is enormous, and it is entirely predictable: the saving is set by the ratio between tangential and radial shrinkage, which ranges from 1.09 to 2.90 across the woods here.

The most-cited figure on the subject puts flatsawn at quadruple the movement of quartersawn. That is not achievable by any wood in the dataset. Under the shortcut that same article proposes, its own answer would be two. Real ratios run from 1.09 to 2.90, and 2.90 is a single outlier — the great majority sit between 1.4 and 2.2.

Quartersawn does not mean it stops moving

Quartersawn white oak still shrinks 5.6% across its width from green to ovendry. That is a real number and it is not small. What changes is which figure applies: the radial one governs width instead of the tangential one, and radial is always the smaller of the two. Sawing does not alter the wood's properties, it just decides which property you have pointed at your problem.

The trade is visible in the drawings. Quartersawn wins in width and gives it back in thickness, where the tangential figure now applies. For a tabletop that is an excellent bargain, because nobody cares about a thousandth of an inch across the thickness. For something where thickness is critical it is not free.

What you actually gain is flatness

The width saving is worth having, but the reason cabinetmakers pay for quartersawn stock is that it stays flat. In a quartersawn board the rings run through the thickness, so both faces shrink by the same amount and there is nothing to drive a cup. In a flatsawn board the two faces shrink differently and the board bends away from the heart. That difference is why quartersawn is specified for door panels, drawer sides, and anything wide that has to stay true — the width figure is a bonus.

Riftsawn: an honest note

The tool offers riftsawn and marks the result as an interpolation, because no primary source publishes a riftsawn coefficient. The Wood Handbook draws one line at 45 degrees of ring angle: below it is plainsawn, above it is quartersawn, and "rift" appears in the document only as a grading term for oak flooring. Four calculators found in research offer a rift option and none says where the number came from. Splitting the difference between radial and tangential is a defensible estimate. It is not a measurement, and presenting it as one would be inventing data.

Asked at the bench

How do I tell what I have?

Look at the end grain. Rings running roughly parallel to the wide face, in long arcs, means flatsawn. Rings running roughly perpendicular, straight through the thickness, means quartersawn. Diagonal is riftsawn. The commercial line is 45 degrees, and boards near it get called bastard sawn between about 30 and 60.

Is quartersawn worth the extra money?

For a wide tabletop, a door panel or anything that must stay flat, usually yes — you are buying flatness more than width stability. For narrow stock it rarely matters, because a 60 mm board does not move enough for anyone to notice whichever way it was cut. Check the T/R ratio for your species first: on a low-ratio wood like walnut or ipe the premium buys much less than it does on white pine or black oak.

Does riftsawn look different?

Yes, and that is often the point. Quartersawn oak shows the medullary ray fleck that people either seek out or avoid; riftsawn gives you straight grain without much of the fleck, which is why it is specified for furniture legs where four faces need to match. That is an appearance decision that happens to have a movement consequence, rather than the other way round.

Why does the drawing show quartersawn cupping slightly?

Because it is not quite zero. Even with the rings running through the thickness there is a small asymmetry across a real board, and the drawing shows a token amount rather than a perfectly flat line so the comparison reads honestly. In practice you can disregard quartersawn cupping beside what a flatsawn board of the same wood will do.